At present, economic losses in crops and animal products caused by insects and other destructive airborne biota undoubtedly exceed $10 billion annually in the United States alone. It is reported that combined costs of insect damage and control measures exceeded $1.4 billion in cotton production alone in 1997. Insects and other arthropods and biota (e.g., fungal spores, bacteria, viruses) cause direct damage to food, fiber, and animal products and plants. Additionally, mosquitoes, flies, and the like also transmit diseases which adversely affect humans and other animals and plants. Losses further extend to orchards and forestry products, and ornamental plants and lawns. Costs further associated with insect pests and other harmful biota include costs associated with insect scouting and control measures. Control measures frequently employ pesticides or the like which also kill beneficial insects, leave residues in food and fiber products, and cause environmental and ecological damage from runoff. Envionmental and ecological damage can also be caused from waste products resulting from chemical pesticide production processes. In food product production animals, it is often necessary to inject antibiotics and other chemicals in order to control pests (e.g., screw worms, hookworms) which have invaded a body of an animal, and such chemicals may cause undesirable side effects or leave residues in products derived from animals.
In many cases, pests are developing tolerance to common pesticides and antibiotics, requiring development of more potent and more selective pesticides and antibiotics which in turn become more expensive. More recently, genetic engineering techniques are being used to introduce genes in some crop species which enable plants themselves to manufacture chemicals within plant material which are toxic to certain insects or other pests. Long term effects of residues and byproducts in human diets, and in the global environment, resulting from use of pesticides, antibiotics, and genetic engineering techniques, and loss of genetic diversity in genetically engineered crops (due to the expense in developing multiple transgenic varieties), are matters of considerable concern and debate. Biological controls employing parasites or disease organisms specific to certain insect pests are currently used in some areas, but use of biological controls suffers in many cases from the lack of timely information on populations, behavior, and movement of targeted pests.
In addition to pests, the overall insect and biota population in a crop field, animal production area, or other outdoor and indoor (e.g., barn, slaughterhouse or similar areas) environment includes many beneficial insects, or “beneficials,” such as bees, parasitic wasps, lady bugs, lacewings, and geocorid bugs as well as other biota such as spiders floating on gossamer threads and some fungalspores and viruses, which are economically important to crops or the ecosystem in general as pollinators or as predators of insect pests. Other insects which may be found in crop fields, animal production areas, and other areas may be neither friend nor foe to a particular crop or production animal, but may be important to other crops or in other areas of the ecosystem. These organisms are designated “neutrals” or “background” insects relative to a specific crop or production animal where they are neither pests nor beneficials. An entire population of insects and other biota in a given region at a given time may be considered to be composed of pests, beneficials, or neutrals relative to a given crop production activity or other activity (e.g., animal production, recreation). For purposes of this application, this aggregated population is designated as a PBN (for pests, beneficials, and neutrals) complex.
Most of the insect species economically important (good or bad) to the production of crops and animal products have an adult stage which is winged and capable of airborne flight. Many fly into crop fields from other nearby host plants and habitats during the growing season when the crop has developed to a stage of their liking, or, in some areas, when the crop is being irrigated and is in a lush condition, and other host plants outside crop fields are drying up. Other insect pests may fly randomly about an animal production environment, such as a feedlot operation, seeking to lay their eggs, or suck blood, causing pain and stress to animals, reducing productivity, and frequently spreading diseases or other parasites. Some, especially moths, may migrate over extremely long distances (hundreds of kilometers), aided by atmospheric winds, to later land in crops and other areas and lay eggs or otherwise cause damage. In many insect species, it is the larval stage of the insect pest which causes the damage. In other species, nymph and adult stages cause the damage and spread diseases, and in some species (e.g., boll weevil), both larval and adult species cause damage.
It is important that control measures (i.e., means of killing, incapacitating, or repelling pests) minimize negative impacts on beneficial insects and other beneficial biota such as bats, most birds, or even pollen grains for production crops. Also, it is generally desirable, from an ecological viewpoint, that control measures also minimize negative collateral effects on the “neutrals” as well.
Current methods of dealing with most pests in crops involve use of crop entomological or agronomical human scouts who have knowledge, experience, sample collection tools, and sampling techniques to identify which species of pests (including harmful fungal and disease organisms in addition to insect pests), as well as beneficial species (also including some fungal and disease organisms which attack pests), are present, and estimate their relative numbers or concentrations. In order to determine whether insect pest population buildup is occurring, and to determine the need for control measures, or whether control measures are being effective, it is important to estimate actual (by traps, sweep nets, direct observation, etc.) or potential (from egg lays) populations of insect pests as well as populations of their respective predators (beneficials). After considering the populations of specific pests estimated to be present in the field or other environment, and populations of their respective predators, decisions are made concerning application of pesticides or other control measures such as releasing additional predators. Economics of labor-intensive crop scouting generally permit sampling only once per week or so, and then only at relatively few sampling sites within the field environment. In some cases, pest populations are also monitored by the use of baits and traps employing general attractants (sweet substances, putrid substances, ultraviolet light, etc.) or species specific attractants, such as sex attractant pheromone chemical complexes which are generally species specific. Generally, such traps must be manually inspected and emptied to determine the species and numbers of insects trapped. Vicki et al (U.S. Pat. No. 5,005,416) describe a pitfall trap employing vibration detection to detect presence of insects in the trap and suggest that the trap might be used with a radio telemetry device. However, they do not describe an overall system concept within which such a telemetry-equipped trap might be used in a field crop or animal production environment, nor do they describe specifics of a telemetry device which might make such an application economically feasible. Many researchers have noted insect activities (e.g., flying, crawling, chewing, chirping) in crops, crop storage bins, and other areas are frequently accompanied by sounds or vibrations detectable by microphones or vibration transducers. Other researchers (e.g., Claridge 1985; Bell 1980) have noted that certain species of insects (e.g., leafhoppers) create vibrations in plants by thumping on the leaves or other plant elements with their legs or by other means, which vibrations travel through the plant material and structure where they may be detected by other insects (perhaps mates or perhaps predators). Various researchers have confirmed presence of such vibrations in laboratory environments using various means, including use of an instrument called a laser Doppler vibrometer (LDV) or sometimes simply laser vibrometer (e.g., Michelsen 1982). A laser Doppler vibrometer typically operates by modulating a transmitted laser beam with an RF signal by use of a Bragg cell or similar mixing device, directing a modulated signal onto a leaf surface or other surface to be monitored for vibrations, gathering light scattered from a surface material with suitable optics, mixing a returned laser signal first with a replica of the laser (carrier) wavelength (as in heterodyne detection) to recover an RF mixing frequency, then mixing the thus recovered (received) RF signal with a replica of the original RF mixing frequency to recover any additional modulations impressed on the composite laser and RF signal scattered from the sampled surface, which additional modulations may be caused by Doppler effects resulting from the relative motions of the surface with respect to the laser source or by other modulation sources, such as atmospheric effects (e.g., scintillation effects) on laser propagation. The detection circuits for the residual vibrations are typically designed so that an output voltage is proportional to the Doppler shift of the signal—see, for example, an Instruction Manual accompanying the Dantec DISA 55×-Laser Vibrometer. Although laser vibrometer instruments have been used by researchers in laboratories to study insect behavior and communications, laser vibrometry has apparently not been previously considered for adaptation for use in monitoring crops for evidence of insect activity, or for other potential applications in monitoring crop health and status, as proposed by Applicants.
Numerous techniques other than chemical pesticides have been employed or proposed for control of insects. Sometimes baits and traps are used for insect population control as well as population sampling. Such methods may be relatively effective indoors but are generally less effective, or costly to implement and maintain, in large field crop environments. Some have proposed use of lasers and other directed energy devices to kill insects, but have not described how such technologies could be employed safely in a field crop or animal production environment, or how lasers could be used without killing or injuring significant numbers of beneficial or neutral insects as well as pests. Johnson (U.S. Pat. No. 5,343,652) suggests that a laser beam could be scanned throughout a crop field with an energy level high enough to injure at least some sensory organs of insects, but does not reveal how injury to beneficial insects such as honeybees would be avoided. Johnson also suggests that a laser beam having sufficient power to incapacitate or kill an insect could be scanned through a crop without substantially harming crop plants, but offers no data to substantiate this statement. In fact, the growing tips and fruit setting blossoms of plants are quite sensitive and would probably be damaged by a laser used as proposed by Johnson, or by high power microwave energy used in a similar way. Some plants are also sensitive to exposure to light, using the durations and other properties of light exposures to trigger or alter various metabolic processes. In suggesting that the laser beam be scanned just above the crop to contact and kill or injure insects, Johnson also acknowledges this embodiment should be used only in remote areas so that accidental exposure of a human or non-target animal is avoided. Further, indiscriminate use of laser beams to attract and kill or incapacitate insects, as proposed by Johnson, would likely result in injury to eyes or other organs of beneficial insects, birds, and bats as well as people and other animals. In fact, implementation of such an approach would likely be prohibited by the Food and Drug Administration (FDA), the Federal Aviation Administration (FAA), the Occupational Safety and Health Administration (OSHA), or other regulatory organizations which impose strict limitations on the use of unconfined laser beams in outdoor environments. Sensor technologies that detect initial incoming adult stage of arriving insects or other pests and provide a useful level of discrimination between potentially harmful and non-harmful insect species could, as a minimum, permit more timely and effective crop scouting. By “useful level of discrimination,” we mean a capability to provide a level of discrimination useful either in terms of supporting more effective scouting (knowing, for example, when a flight of moths has arrived in a field, even though specific moth species is not determined by sensor technologies) or which is useful in supporting decisions on selection and employment of specific control measures. For example, ability of a set of sensors to distinguish moths from wasps and honeybees, and estimate gross populations of each group (i.e., all moths, all wasps, etc.) would not, in and of itself, be adequate information to support a decision to make a pesticide application without identification of specific species present and confirmation of their populations by scouts. However, such sensors may be very useful in signaling arrival of a migratory flight of moths, and thereby alerting a crop producer or his entomological consultant of a need to scout a field in question to determine whether populations of specific pest species exceed thresholds for a pesticide application decision. Information from such sensors on quantity of wasp-like insects observed in, or entering or leaving, a particular field would also be useful in estimating a balance between pests and their predators to support a pesticide application decision.
When a modest sensor capability to detect insects in flight and simply discriminate potentially harmful insects (e.g., moths) from other airborne biota (e.g., wasps, honeybees, and June bugs) is combined with knowledge, for example, that there are virtually no moths which are beneficial, or at least economically important, to most crops (e.g., cotton), the silkworm moth being an obvious exception, an opportunity is opened for a control strategy which may simply destroy or incapacitate all moths (of a certain size range) which are observed entering a crop field of a crop for which there are no beneficial moths. Thus, in this example, the synergistic combination of even a modest discrimination capability with an immediate, precision kill technology would provide a significant benefit in preventing damage to crops by moth pests. Killing or incapacitating moths or other pests before they enter the crop and lay eggs also has significant advantages over most conventional control techniques which attempt to control pests only after they have entered the field and established certain threshold populations which then need a pesticide application. The utility of such a capability is enhanced by extension of the capability to distinguish among (i.e., perform “classification” of, or “discrimination” between) other insect pests, beneficials, and neutrals.
It has been established by other researchers that even modest radars, such as modified marine radars, are capable of detecting insects in flight and measuring selected parameters (e.g., wing beat frequency, amplitude vs polarization, overall radar cross section) which support at least a partial classification separation of different species (e.g., most moths from most wasps). Schaeffer (R.E.S.(Royal Entomological Society) Symposium 7, Insect Flight, 1976), for example, reported that, by using a modified X-band marine radar, he was able to collect radar returns from locusts and butterflies flying overhead which would permit him to distinguish one from the other by performing Fourier transforms on amplitude time histories observed in a series of returns from radar pulses as each respective insect was flying through a radar antenna beam. In the Fourier transforms, it was possible to distinguish peaks at different frequencies corresponding to respective wingbeat frequencies of a locust and butterfly, and in the data from a locust, other peaks were observed at frequencies attributed to respiration rate of the locust (since, in breathing, shape of the locust's body changes, causing modulation of amplitude of the radar cross section, and hence changes in the amplitude of a radar return, at periodic cycles corresponding to the respiration rate). Most researchers in this field believe that ability to detect wingbeat frequencies is due to changes in shape of an insect's body as it flies, rather than being due to radar returns from wings themselves, since material in insect wings is virtually transparent to radar frequencies used in past measurements (Schaefer, 1976). Wolf (personal communication, 1998) reports that he has been able to observe individual moths and boll weevils in flight at altitudes well above crops and other vegetation (avoiding a ground clutter problem), and has also identified several measurements which can be made by radars to aid in the classification of an observed insect as being a moth as oposed to, for example, a wasp. However, when only conventional pest control measures employing chemical pesticides are available, because of the environmental concerns and the regulatory controls being applied to prevent unnecessary or excessive use of chemical pesticides, it is becoming essential to also know specific species of moths present in a crop field.
As noted earlier, another key limitation in use of radar for insect detection and monitoring applications is that, when insects descend to too low a level (e.g., less than ten to twenty feet above a ground level or crop canopy), or originate or maintain flight at a low level above the ground or vegetation (e.g. grass, crop canopy), as when flying into a crop from weeds or other plants in the vicinity of the crop), insects generally can not be detected by conventional radar since the amplitude of “clutter returns,” resulting from inevitable sidelobes of a radar antenna pattern illuminating the ground and vegetation in the same range cells as insect targets, will generally exceed amplitude of the return from an insect, so that insect signal-to-noise-plus-clutter ratio is below detectable limits. Since some clutter returns generally occur from the same ranges as targets, use of range gating in the radar cannot eliminate the clutter. Even when more sophisticated radars employing Doppler measurement capabilities and advanced signal processing are employed, Doppler spread resulting from motion of vegetation due to wind, heliotropic tracking, and growth will frequently interfere with detecting Doppler shifted or Doppler spread return from an airborne insect. Costs of radars also increase appreciably when very stable oscillators and other components are required to support more sophisticated measurements and signal processing which may be needed for suppression of clutter and other noise sources.
As stated, a laser beam may be scanned rapidly over a crop to detect insects, as suggested by Johnson. However, the top of the crop canopy is not a well-defined plane, but includes multiple growing plant tips standing with random height variations of 0.5 meters or more, and with significant room between the plant tips. Once moths and other insect pests enter a crop, they are “at home” and have little requirement to fly higher than the growing tips of the crop plants. Consequently, pests generally spend little if any time in flights higher that the growing tips of the plants, and there is little opportunity to detect and contact such pests once they have “settled into” a crop. Most beneficial insects, however, have nests or other domiciles outside the crop, only entering the crop to collect nectar (and thereby aiding pollination) or to seek out insect pests (e.g., larvae, grubs, or caterpillars, and in some cases adult insects) dwelling and feeding on the crop plants. Since beneficials are generally traveling further distances to enter a field and return to their generally out-offield domiciles, and since pollinators are generally working flowers of the crop, which are generally located near the top of the crop, beneficial insects are generally more likely to be flying higher, above growing tips of the plants, than are the pests. Consequently, a laser beam simply scanned above the top of the crop is more likely to contact and injure beneficial insects than insect pests. As noted earlier, Johnson did not disclose a need or a method for distinguishing insect pests from beneficial insects and neutrals. Even if a laser alone is used to perform initial detection of an insect, information from individual “hits” on the insect as the laser scanned the field would not be sufficient to collect observational data needed to support classification of a “target” as pest or non-pest. Consequently, simply using a laser beam alone to scan a field and contact and injure insects, as suggested by Johnson, would have limited effectiveness in detecting insect pests “working” the crop, and would probably be more likely to injure beneficial insects than pests.
As described above, radar and ladar sensor technologies separately have some capabilities for detecting insects in flight above a crop, but also have significant limitations when employed separately to detect insect pests present within crops. When radar is deployed in a crop field environment as described in the literature, it has significant difficulty in simply detecting insects in or just above a crop, much less obtaining measurement data needed to support classification. Johnson did not disclose any capability for classification of insects, nor for providing for safe use of lasers in a field crop environment (other than suggesting that they be used only in remote locations).
The instant invention takes advantage of synergistic combinations of radar and laser sensor technologies with other features of the invention relating to specific geometries and use of special configurations and materials which enhance capabilities of radar and laser sensors to overcome clutter and background noise problems to detect insects and other airborne biota and provide measurement information to permit a useful degree of classification as pest, beneficial, or neutral. The invention also includes, in some embodiments, use of additional observations and measurements by other optical sensors (e.g., hyperspectral or multispectral sensors, or sensors capable of monitoring intensity ratios of selected spectral lines or bands). Another major synergistic combination occurs in enhanced embodiments wherein immediate precision kill technologies directed generally against individual insects or other airborne biota specimens classified as pests are integrated with detection and classification capabilities provided by combined radar and optical sensors. An integrated system embodiment based on methods of the present invention can detect, classify, and kill or incapacitate insects and other airborne pests before they enter a crop or animal production environment and lay eggs or otherwise begin their damage.
When such sensor technologies as advanced radar and ladar, which are capable of determining location of individual airborne insects and which together or in conjunction with other optical sensor technologies are capable of providing remotely sensed measurements which can support a classification schema capable of distinguishing most insect pests from beneficial or neutral insects, are combined with advanced control technologies which can destroy or incapacitate an adult pest before eggs are laid or damage is inflicted on protected assets, the resulting system has a major advantage over techniques and technologies which must wait until eggs are laid and/or plant and fruit damage is incurred to determine which specific species are present and which pesticides should be applied (and are permitted by regulations) for that species